This invention relates to newly identified polynucleotides, polypeptides encoded by such polynucleotides, the use of such polynucleotides and polypeptides, as well as the production of such polynucleotides and polypeptides. More particularly, the polypeptide of the present invention is human homolog of the bacterial AlkB gene, sometimes hereinafter referred as xe2x80x9chABHxe2x80x9d. The invention also relates to inhibiting the action of such polypeptides.
Alkylating agents induce DNA damage which may cause either killing of cells or induction of mutation and cancer. Most of such damage is subjected to common cellular DNA repair mechanisms, such as excision repair and postreplication repair (Hanawalt, P.C., et al, Annu. Rev. Biochem., 48:783-836 (1979) and Witkem, Bacteriol. Rev., 40:869-907 (1976)). A repair mechanism is that performed by the human DNA mismatch repair protein.
Certain strain of E. coli mutants have been found to be specifically sensitive to alkylating agents. Two types of such mutants have been isolated, alkA and tagA (Yamamato, Y., et al., J. Bacteriology, 135:144-152 (1978) and Karran, P., et al., J. Mol. Biol., 40:101-127 (1980)). These genes control the formation of enzymes that catalyze the liberation of certain alkylated bases from damaged DNA (Karran, P., Nature (London), 296:770-773 (1982)). In addition, ada and adc mutants have been isolated which are defective in controlling mechanisms to induce the adaptive response to alkylating agents (Jeggo, P., J. Bacteriol., 139:783-791 (1982)).
The tagA gene has been mapped to an E. coli chromosome and controls a constitutive enzyme 3-methyladenine-DNA glycosylase I that releases 3-methyladenine from alkylated DNA (Karran, P. et al., Nature (London), 296:770-773 (1982)). The alkA gene has also been mapped and it too controls an inducible enzyme, 3-methyladenine-DNA glycosylase II, which catalyzes the liberation of 3-methyladenine, 3-methylguanine, and 7-methylguanine from the DNA (Evensen, G. and Seeberg, E., Nature (London), 296:773-775 (1982).
Another gene of E. coli, AlkB, has also been found to control sensitivity to methyl methane sulfonate (MMS). The AlkB gene was located in a region of the chromosome near ada and adc, but is not considered an allele to these genes (Sedgwick, B., J. Bacteriol., 150:984-988 (1982)).
Thus, AlkB resides in a new gene that is near the na1A gene. The AlkB phenotype is different from that of ada, since the AlkB mutant exhibited a normal adaptive response to n-methyl-nxe2x80x2-nitro-n-nitrosoguanidine (Kataoka, H., et al., J. Bact., 153:1301-1307 (1983)). The AlkB gene of E. coli has been found to be responsible for the repair of alkylated DNA (Kondo, H., et al., J. Biol. Chem., 15:1-6, (1986)).
Due to the amino acid sequence between AlkB from E. coli, the present polynucleotide and deduced polypeptide have been putatively identified as a human homolog of the E. coli AlkB protein.
In accordance with one aspect of the present invention, there is provided a novel mature polypeptide which is hABH, as well as fragments, analogs and derivatives thereof. The polypeptide of the present invention is of human origin.
In accordance with another aspect of the present invention, there are provided polynucleotides (DNA or RNA) which encode such polypeptides.
In accordance with yet a further aspect of the present invention, there is provided a process for producing such polypeptide by recombinant techniques.
In accordance with yet a further aspect of the present invention, there is provided a process for utilizing such polypeptide, or polynucleotide encoding such polypeptide for therapeutic purposes, for example, for repairing alkylated DNA and accordingly preventing or treating cell death and cancer.
In accordance with yet a further aspect of the present invention, there are provided antibodies against such polypeptides.
In accordance with yet another aspect of the present invention, there are provided antagonists to such polypeptides, which may be used to inhibit the action of such polypeptides; for example, to prevent this polypeptide from repairing tumor cell DNA during chemotherapy with alkylating agents.
These and other aspects of the present invention should be apparent to those skilled in the art from the teachings herein.